Congenital abnormalities (also called congenital anomalies)
of the upper extremity are differences from normal that are present at birth.
The differences can range from mild to severe. Examples of congenital abnormalities
in the hand include: having more than or fewer than five fingers; fingers that
won't bend; fingers that are too short, crooked, or webbed; and constriction
bands on the fingers and/or hand. Examples of congenital abnormalities in the
arm include: an arm that is bowed, bones and joints that have not formed normally,
and a part of or whole arm that has not formed at all. Some of these differences
are known to happen along with other problems, while some are isolated differences.

What causes them?

There are many causes of congenital abnormalities. Some can
be explained and others have no known causes. The process of development of
a baby from a fertilized egg involves millions of complicated steps, any of
which can go wrong. The upper limbs form between the fourth and seventh week
of pregnancy; the baby is less than an inch long during this phase of development.
It is estimated that one in 20 babies born
will have some imperfection, major or minor.

Some congenital problems are inherited, just like eye or hair color for example.
Some of these inherited problems may skip generations or show up in the children
of parents who each pass on a trait to the child. Some genetic problems are new
occurrences where the new baby is the first to have the condition, but that child
may pass it on to his or her children. Other congenital problems have non-genetic
cause. Certain drugs, such as thalidomide and chemotherapy agents, are known to
cause birth defects. Street drugs, tobacco, and alcohol all affect the development
of a baby but are not generally connected with specific upper extremity problems.
Congenital constriction bands, where threads of the amniotic membrane separate
from the lining and become wrapped around the fingers and/or hand, can cause deformity
in some babies during pregnancy. Although we understand how constriction bands
happen, the cause is mostly unknown.

Congenital problems sometimes happen with no explanation as to when, why, or to
whom. One of the many steps in the development of the baby went wrong and changed
the arm or hand. Your physician can help you find answers to your questions about
what happened and, if possible, why it happened. Your physician may refer you
and your child for more studies and possibly a visit to a geneticist to help with
a specific diagnosis and determine whether the condition is hereditary.

Coping with your emotions

Shock, anger, and guilt are normal emotions after the birth of
a child with a congenital abnormality. All of your dreams of the perfect baby
did not take place, and now each family member must cope with their feelings.
Rarely is there anything parents could have done differently— yet they blame
themselves.

Your newborn doesn't realize that he or she is different. The baby has all the
normal needs of any newborn. The way the baby has formed is normal for him or
her; without pain and without a sense of loss. After your grief has eased, questions
will follow: Is there any treatment for this problem? Will surgery help? Will
my child be able to tie shoes or hold a pencil? Talk to your pediatrician and
hand surgeon about resources available such as support groups, therapists, and
caring physicians to help you and your child.